Cashflo

What is an afc hack? Can a s-afc work on a b16 or would i have to get the v-afc? I got a set of dsm injectors, but dont know where to get a resistor box and how to hook it up? And last but not least, whats a good ignition set up? any help would be appreciated.

rjardy

uh oh
http://www.thedropshop.tv/vafc.htm

https://honda-tech.com/zerosearch

try these......

Rob

legendboy

https://honda-tech.com/zerosearch

filetofit

An AFC hack stands for air fuel cough, hack. It's when you've been working in your garage too long sniffing gas and oil vapors and you go out in the fresh air and cough .... hack. No seriously it's when you use an apex-i fuel correction computer to alter the MAP sensor voltage signal that the ECU "sees". The MAP sensor voltage is a major part of how the ECU determines how much fuel to inject. By reducing the MAP sensor signal from say 5 volts to 3 volts you are telling it to provide less fuel (a shorter duration injector pulse) but by using larger injectors you get more fuel per pulse, so the two effects cancel each other. Why bother? Because your ECU will set a check engine light for 5 volts, (which corresponds to 11 psi of boost) bot won't set a CEL for 3 volts. And a SAFC should work as well as a VAFC, but the VAFC computer can alter the VTEC engagement point as well.

X2BOARD

I have heard that the AFC can make a missing link valve useless (doesn't need it) I understand that it alters the MAP sensor voltages, but how does it handle getting enough fuel while under boost ? Or can it ONLY do that with larger injectors ?

X2

DC2R714

hmmmmmmmmmm. ah yes there it is.



: Puts on flame retarded jumpsuit

X2BOARD

Woo hoo... that one REALLY helps out... please avoid posting useless garble here... you might want to frequent 'Member's Corner'...... PW ing is Ok there...

X2

filetofit

The AFC can add fuel with stock injectors by increasing the MAP sensor voltage that the ECU sees, but then of course you will trip a CEL that much earlier. This application of the AFC only works to add small amounts of fuel for NA mods. With boost you have to use larger injectors and use a large cut in the MAP sensor output. Think of it this way, with the VAFC hack your vaccum range on the MAP sensor goes from 0.0-3.0 volts to 0.0-1.6 volts (approximately). Then the MAP sensor range from 1.6-3.0 volts is used for boost.

X2BOARD

So even under boost, it intercepts the MAP signal to avoid the ecu seeing boost ? I would assume the fuel pressure must also be altered (particularly w/ larger injectors). So does that mean an AFC w/ stock injectors only allows minimal adjustment ?

X2

filetofit

Yup

Yes

Fuel pressure should remain stock. You're fueling needs under boost are taken care of by the larger injectors. However you may need to add more fuel back at idle with the VAFC because large injectors take longer to open and for short pulsewidths they deliver less fuel than you would expect based on injector size alone.

PolySquared

is this afc hack just an alternative for hondata? i plan on boosting my car soon and i dont know what to do. I would like the cheapest way.

integragsr6

do you have to use the 450cc injectors or can you use larger ones for this hack?

filetofit

The hack combined with 450cc injectors takes care of the boosted fueling needs. However you still need to consider a boost dependant timing retard device such as the MSD BTM. I'm not sure why people are so crazy about the hack becuase when you add together the cost of a VAFC and the MSD BTM it comes out close to what you would pay for OBD1 hondata. Of course, you could build your own circuit for about $20 like I did to do the same thing as the VAFC and save $280.

X2BOARD

I already have a BTM on my car... so that's not an issue for me, but why do you NEED a BTM as many FI people run either stock or retarded timing. I personally ran advanced with the BTM set at 0.75 at 8psi.

I have also heard the VAFC will not run bigger than 440/450's injectors !?

How did you make a circuit that replaces the afc ??? How does it compensate... or is it rpm based ?

X2

filetofit

Well, OK the BTM isn't a NEED but some sort of timing retard is recommended if you are going to boost 11 psi (which you can with 450 cc injectors). For lower boost I guess stock timing is OK. Just a little extra safety and driveability with the BTM. As for the circuit, it's not as sophisticated as the VAFC in that it is not RPM dependant. It just uses analog electronics (op amps) to adjust the MAP output passed to the ECU. It only provides two points of adjustment, idle and WOT. But then again most people just apply -50% across the board with the hack so you don't really need 8 rpm adjustable points for that.

http://www.angelfire.com/ab7/diymaplimiter

PolySquared

good information! keep on going!

filetofit

If you haven't already, read my last post on the subject in:

https://honda-tech.com/zerothread?id=247161